I am a prime number.
The double of myself is equal to the square of me.

which number am I?

What is a word made up of 4 letters, yet is also made up of 3. Sometimes is written with 9 letters, and then with 4. Rarely consists of 6, and never is written with 5.

You need to move three matchsticks to form three squares. Can you do it?

Can you find out a way through which you can make five squares out of the given figure by moving just six match sticks?

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

When we see 2 but call 10?

How much will a 38° angle measure when looked at under a microscope that magnifies ten times?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

You have a thousand Re. 1 coins with you. You have ten bags with you and you can put any number of coins in each of the bags. The condition is that if someone asks you for any amount between 1 and 1000, you must be able to give that amount by just giving the bag (you are not allowed to open the bag and give coins).

How will you do it?